1. Field of the Invention
The present invention relates to cephalosporins having a methoxy group at the 7.alpha.-position and also to processes of producing the cephalosporins. More particularly, the invention relates to 7.alpha.-methoxy-7.beta.-heterocyclic thioacetamido-3-heterocyclic thiomethyl-.DELTA..sup.3 -cephem-4-carboxylic acid represented by the general formula ##STR1## wherein R.sup.1 represents ##STR2## (wherein R.sup.3 and R.sup.4, which may be the same or different, each represents a hydrogen atom, a hydroxy group, an amino group or a lower alkyl group; n represents 0 or 1; R.sup.5 represents a hydroxy group, an amino group, a mercapto group, a lower alkylamino group, a lower alkanoylamino group, a lower alkoxycarbonylamino group, a carboxy lower alkylthio group, or a 3-lower alkylureido group; and X represents --CH.dbd. or --N.dbd.) and R.sup.2 represents a 5-lower alkyl-1,3,4-thiadiazol-2-yl group or a 1-lower alkyltetrazol-5-yl group, and the pharmaceutically acceptable salts thereof.
2. Description of the Prior Art
Cephalosporin derivatives having a methoxy group at the 7.alpha.-position, a heterocyclic acyl group at the 7.beta.-position, and a heterocyclic thiomethyl group at the 3-position are known. For example, U.S. Pat. Nos. 4,017,488 and 4,051,129 discloses 7.alpha.-methoxy-7.beta.-(5-methyl-substituted or unsubstituted)-1,3,4-thiadiazol-2-yl-thioacetamido-3-(1-methyltetrazol-5-y l)-thiomethyl-.DELTA..sup.3 -cephem-4-carboxylic acid. Furthermore, Japanese Patent Application Laid Open No. 52,195/'76 discloses 7.beta.-(2-amino-4-thiazolyl)acetamido-7.alpha.-methoxy-3-(1-methyltetrazo l-5-yl)thiomethyl-.DELTA..sup.3 -cephem-4-carboxylic acid. Other similar compounds are also described in, for example, U.S. Pat. No. 3,887,549; Dutch Pat. No. 7,216,268; German Offenlegungsschriften Nos. 2,440,790, 2,448,582, 2,445,341, and 2,455,884 and British Pat. No. 1,412,886.